Psoriasis is a disease of the skin, whose etiology is unknown. The skin lesions associated with psoriasis may be described as dull red patches or plaques of scaly erythema. The scales are distinctive, having a slightly opalescent silvery appearance. The disease has a predilection for certain areas of the body; thus the scalp, the extensor surfaces of the extremeties (particularly at the elbows and knees), the back and the buttocks are most usually affected. However, the nails, eyebrows, axillae, umbilicus and anogenital regions are also frequent sites of involvement.
To date, there has been no report of a complete and permanent cure for psoriasis, and although the several treatments of choice available afford temporary remission of the symptoms, recurrence is almost certain. Most treatments involve the topical application of steroid (e.g. the adrenocortical steroids) ointments and creams, and no clinically successful, long-term, systemic treatment for the disease is currently available.
The compounds utilized in the process of the invention, substituted benzylideneamino-3-hydroxyguanidines and their pharmacologically acceptable acid addition salts, have previously been described in the literature. For example, U.S. Pat. No. 3,591,636 described the preparation of this class of compounds and discloses their utility as hypotensive agents and agrochemicals (i.e. antifungals and herbicides). In addition the preparation of the substituted benzaldehydes from which the benzylideneamino-3-hydroxyguanidines of the invention may be prepared is described in Chemical Abstracts, 26, 1271 (1931); 31, 3816 (1936).